The interface atomic structure of very thin IrSi(IrGe) films grown on the Ir(001) plane has been studied with the field ion microscope. Two distinctive types of structures have been observed. One shows the C(2×2) structure of the substrate. As the size of the layer is reduced by field evaporation, the surface relaxes into a rhombic structure resembling the (011) Ir layer of the IrSi(IrGe) crystal. The other shows a rectangular unit cell of a larger size, which is not yet successfully correlated to the structure of the IrSi(IrGe) crystal.

Thin single crystal NiSi2 films have been grown epitaxially on the [111] oriented Si tip surface in ultrahigh vacuum (UHV). A 180° change in the axial symmetry is found for the field ion images taken before and after the growth of the silicide layers. From this observation and a computer simulation of the field ion images we conclude that the Si-NiSi2 interface has the B-type structure. The field ion image of the NiSi2 films is good enough to reveal the atomic structure of the (111) Ni layer.